textproduct: Albany

WHAT HAS CHANGED

The arrival of light snow from our clipper disturbance on Friday has trended later now holding off until late Friday afternoon or Friday evening.

We blended NBM/NBM90th percentile guidance for wind gusts this weekend given increased confidence for a persistent tight pressure gradient supporting continued gusty winds Saturday through Sunday. The prolonged period of strong winds and frigid temperatures has increased confidence for dangerous cold this weekend.

KEY MESSAGES

1) Minor impacts mainly from slippery travel Friday night into early Saturday due to a period of snow showers and potential snow squalls.

2) Moderate to high confidence in very cold temperatures and persistent gusty winds Friday night through Sunday night resulting in a prolonged risk for dangerous cold and an increased risk for hypothermia and frostbite.

DISCUSSION

KEY MESSAGE 1...

While a few moisture starved shortwaves track across the Northeast this week resulting in a few instances for isolated to scattered snow showers, especially in the southern Adirondacks and southern Greens, the next chance for more widespread light snow holds off until Friday/Friday night. We continue to closely monitor an initial shortwave tracking out of the Great Lakes and Ohio Valley that looks to phase with a more potent closed low diving southward from the Hudson Bay. The arrival time of this initial shortwave has trended later and therefore the surge of warm air and moisture advection ahead of it has trended later in the day Friday so the timing of the initial period of light snow now looks to holds off until Friday P.M/evening. Meanwhile, a more potent closed low near the Hudson Bay digs southward Friday night and guidance continues to suggest that the two at least partially phase by early Saturday resulting in surface cyclogenesis off the New England coast. While overall forcing and moisture late Friday P.M into Friday night remains weak, the incoming warm air/moisture advection in the low and mid- levels combined with forcing intersecting the DGZ at times looks sufficient enough to support a widespread light snowfall event. The westerly/upslope flow should also enhance snowfall amounts in the Taconics, southern Greens, northern/eastern Catskills and southern Adirondacks. As noted in the previous discussion, the timing of this event being nighttime and into a weekend should minimize impacts and WPC's probabilistic WSSI continues to show under 20% chance for minor impacts or minor inconveniences to daily life. As the main trough axis and associated Arctic cold front sweeps through the region from west to east early Saturday morning, there is still a low chance for isolated to scattered snow squalls but again the weekend timing should minimize impacts. Bottom line, if you plan to be out and about Saturday morning, give yourself extra time due to slippery travel from widespread light snowfall falling overnight into the early A.M hours.

Latest probabilistic guidance from the NBM only shows a 15-30% chance for QPF amounts to exceed 0.10" and even with elevated snow-to-liquid (SLRs) ratios over 15:1, this still equates to widespread snowfall amounts generally falling under 2 inches. The exception is the southern Adirondacks where upsloping likely enhances snowfall amounts but even there is only a 40 to 50% chance to exceed 2 inches.

KEY MESSAGE 2...

Increasing confidence for a prolonged period of dangerous cold beginning Friday night continuing through at least Sunday night as a frigid air mass surges into the Northeast behind our exiting shortwave trough early Saturday. As a sfc low rapidly develops off the New England coast and high pressure builds eastward out of the Midwest, the sfc pressure gradient over the Northeast quickly tightens supporting strong, gusty winds. There is strong agreement that the northwest winds advect an anomalously cold air mass with origins from northern Canada into eastern NY and western New England this weekend. Not only do the NAEFS still show 850hPa temperature anomalies ranging 2 to 2.5 standard deviations below normal, but the latest probabilistic guidance continues to show the 25th and 75th percentile for high temperatures on Saturday ranging between the single digits and teens across much of the region with the southern Adirondacks ranging between negative single digits and positive single digits.

The dangerous cold looks to persist through Sunday night as the parent closed low slowly tracks southward into the Northeast, locking in the cold air advection regime and gusty winds from a continued tight sfc pressure gradient. The combination of cold temperatures and gusty winds this weekend will likely result in dangerous wind chills with medium to high confidence that we will meet cold weather advisory (wind chill values -10F to -15F) criteria throughout eastern NY and western New England and even meeting extreme cold warning criteria (wind chill values -25F to -30F) in the southern Adirondack and potentially in western New England. While these products will likely be issued at night, there is a low chance that we may even need cold weather advisories daytime Saturday in parts of the region. Latest cluster analysis shows that there are still some discrepancies among the guidance on the track of the closed parent cyclone as it dives out of Canada this weekend which will influence when and where the coldest temperatures occur.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

Through 12z/Wed...Patchy low clouds have been attempting to develop at KGFL but failed to develop elsewhere. Outside of a brief TEMPO for KGFL until 13z/Tue, low stratus mentions have been removed for this TAF update. Clouds will approach from the west this morning but will be within VFR thresholds. Cigs may lower to MVFR thresholds at some sites this afternoon as a clipper disturbance approaches with the higher confidence at KPSF. Tonight, mainly low end VFR cigs are expected though some MVFR cigs/vsbys could occur within any passing snow showers or flurries. Have included PROB30 groups at KALB/KGFL/KPSF for a most likely window of snow showers. Wind will be variable at 5 kt or less through much of the TAF period.

Outlook...

Wednesday Night: No Operational Impact. NO SIG WX. Thursday: No Operational Impact. NO SIG WX. Thursday Night: No Operational Impact. NO SIG WX. Friday: Moderate Operational Impact. Chance of SHSN. Friday Night: Moderate Operational Impact. Windy With Gusts To 30 kts. Chance of SHSN...SN. Saturday: Moderate Operational Impact. Windy With Gusts To 34 kts. NO SIG WX. Saturday Night: Low Operational Impact. Breezy. NO SIG WX. Sunday: Low Operational Impact. Breezy. NO SIG WX.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.